1. Field of the Invention
The present invention relates to a sewing machine equipped with a needle threading device which includes a mechanism for giving a tension to a thread of the sewing machine in order to securely insert the thread through a needle hole.
2. Description of the Related Art
Conventionally, there have been proposed various needle threading devices, in order to pass a thread through a sewing needle of a sewing machine. A needle threading device disclosed in Japanese Patent Application Laid-open No. H8-173676 has a needle threading hook at the front end of which there is formed a hooking part that catches a thread. The needle threading device performs a needle threading operation in such a way that the needle threading hook catches the thread that is stretched by a thread holding tool in a state that the thread is tensioned near the needle hole of the string, and the needle threading hook is pulled out from the needle hole.
In the needle threading device, the needle threading hook that has been pulled out from the needle hole is moved upward from the needle hole, in order to more securely pull out the thread from the needle hole. In the upward movement, the thread is detached from a hook part of the hook, based on the frictional force in the needle hole and the weight of the thread itself, and the needle threading operation is completed.